Masking method for semiconductor devices with high surface topography

Abstract

The method comprises the steps of providing a semiconductor body or substrate ( 1 ) with a recess or trench ( 2 ) in a main surface ( 10 ), applying a mask ( 3 ) on the main surface, the mask covering the recess or trench, so that the walls and bottom of the recess or trench and the mask together enclose a cavity ( 4 ), which is filled with a gas, and forming at least one opening ( 5 ) in the mask at a distance from the recess or trench, the distance ( 6 ) being adapted to allow the gas to escape from the cavity via the opening when the gas pressure exceeds an external pressure.

The invention claimed is: 
     
       1. A method of producing a semiconductor device, comprising:
 providing a semiconductor body or substrate having a main surface with a recess or trench in the main surface; 
 applying a mask above the main surface, the mask covering the recess or trench, so that the recess or trench and the mask form a closed cavity, which is filled with a gas; and 
 forming a plurality of openings in the mask, the openings being arranged on the periphery of the recess at a distance from the recess or trench, the distance being adapted to allow the gas to escape from the cavity via the openings when the difference between a pressure exerted on the mask by the gas and a pressure exerted on the mask from outside the recess or trench is larger than a predefined value. 
 
     
     
       2. The method of  claim 1 , wherein the mask is applied as a dry film using a lamination technique. 
     
     
       3. The method of  claim 1 , wherein the mask forms a planar layer above the recess or trench. 
     
     
       4. The method of  claim 1 , wherein the distance is less than 5 μm. 
     
     
       5. The method of  claim 1 , wherein the distance is less than 3 μm. 
     
     
       6. The method of  claim 1 , wherein the gas filling the cavity is captured ambient air. 
     
     
       7. The method of  claim 1 , wherein the gas filling the cavity is nitrogen. 
     
     
       8. A method of producing a semiconductor device, comprising:
 providing a semiconductor body or substrate having a main surface with a recess or trench in the main surface; 
 applying a mask above the main surface, the mask covering the recess or trench, so that the recess or trench and the mask form a closed cavity, which is filled with a gas; and 
 forming at least one opening in the mask at a distance from the recess or trench, the distance being adapted to allow the gas to escape from the cavity via the at least one opening when the difference between a pressure exerted on the mask by the gas and a pressure exerted on the mask from outside the recess or trench is larger than a predefined value, 
 wherein the recess or trench is provided for a through-wafer via or contact comprising a metal layer, and 
 wherein the metal layer is applied to an area of the main surface surrounding the recess or trench, and the mask is used in an etching step to structure the metal layer, so that the at least one opening is transferred to the metal layer. 
 
     
     
       9. The method of  claim 8 , wherein
 the at least one opening is locally confined in such a manner that the metal layer extends from the recess or trench beyond the at least one opening. 
 
     
     
       10. The method of  claim 8 , wherein
 the metal layer is structured by etching, 
 a further layer is applied, 
 the mask is applied on the further layer, and 
 the mask is used to structure the further layer. 
 
     
     
       11. The method of  claim 10 , wherein
 the further layer is a passivation layer, which is also applied in the recess or trench.